INVESTMENT SECURITIES (Details 5) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Amortized Cost
Due within one year	$ 821,310
Due after one year through five years	712,823
Due after five years through ten years	380,657
Due after ten years	1,278,763
Total available-for-sale investment securities	3,193,553
Estimated Fair Value
Due within one year	819,156
Due after one year through five years	718,395
Due after five years through ten years	380,493
Due after ten years	1,287,194
Total available-for-sale investment securities	3,205,238	$ 3,773,226
Amortized Cost
Due after ten years	160,135
Estimated Fair Value
Due after ten years	160,135
Fair value of available-for-sale investment securities pledged	$ 1,110,000	$ 873,000